Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.

Polyporus dictyopus, with a large number of heterotypic synonyms, has been traditionally considered a species complex, characterized by wide morphological variation and geographic distribution. Thus, neotropical specimens previously identified as P. dictyopus from Amazonia, Cerrado and Atlantic Forest biomes were studied based on detailed macro- and micromorphological examination and phylogenetic analyses, using distinct ribosomal and protein-coding genomic regions: the nuclear ribosomal internal transcribed spacer (nrITS), nuclear ribosomal large subunit (nrLSU), and RNA polymerase II second subunit (RPB2). Two unrelated generic lineages, each one represented by different species, are reported: Atroporus is recovered and re-circumscribed to include A. diabolicus and A. rufoatratus comb. nov.; Neodictyopus gen. nov. is proposed to accommodate N. dictyopus comb. nov. and two new species, N. atlanticae and N. gugliottae. Our study showed that at least five distinct species were hidden under the name P. dictyopus. Detailed descriptions, pictures, illustrations, and a key are provided for Atroporus and Neodictyopus species.

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Polyporus subpurpurascens is a rare Neotropical species characterized by deep purplish pilear surface and radially elongated pores. This study analyzed Neotropical specimens from Argentina, Bolivia and Brazil by applying detailed morphological examination and phylogenetic analyses. We conclude that P. subpurpurascens is a species of Neofavolus, and N. subpurpurascens is proposed as a new combination. New records from Argentina and Bolivia, a detailed description, and photographs of the species are included.

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Las especies neotropicales del género Favolus (Polyporaceae, Agaricomycetes) son importantes ecológica y económicamente, causando una pudrición blanca de la madera y siendo utilizadas como alimentos en diferentes regiones. Hasta el momento, no se reportan estudios sobre cultivo, domesticación y distribución de Favolus rugulosus, una especie recientemente descrita para el Neotrópico. Los objetivos de este estudio fueron: evaluar el crecimiento de micelio y basidiomas bajo diferentes condiciones nutricionales y conocer mejor la distribución de F. rugulosus en Colombia. Se revisaron 61 materiales depositados como Favolus en el herbario HUA, solo seis corresponden con F. rugulosus y hasta el momento esta especie solo está reportada en el departamento de Antioquia. Se realizó un aislamiento a partir de un espécimen de F. rugulosus colectado en Medellín (Colombia). La identificación se realizó mediante estudios morfológicos y moleculares utilizando el marcador ITS. Se encontró que el agar glucosa oxitetraciclina fue el medio de cultivo más adecuado para el crecimiento micelial y que el cultivo de los basidiomas fue viable en los dos sustratos evaluados. No se encontraron diferencias significativas en la eficiencia biológica alcanzada en ambos sustratos.

Mycobonia and Pseudofavolus (Polyporales, Basidiomycota) are polyporoid genera with tropical and subtropical distribution. Both genera are morphologically similar in presenting flabelliform to conchate subsessile basidiomata, with a dimitic hyphal system, consisting of clamped generative hyphae and skeleto-binding hyphae that produce large basidiospores with smooth, thin walls. However, while Pseudofavolus species present a poroid hymenophore, in Mycobonia it is stereoid with hyphal pegs that resemble thin teeth. Mycobonia and Pseudofavolus have a controversial taxonomy, and the phylogenetic relationships between their species have yet to be assessed. For this reason, we performed molecular phylogenetic analyses on specimens of Mycobonia and Pseudofavolus from both the Neotropics and Asia, using internal transcribed spacers (ITS), the large subunit of nuclear rDNA (nc LSU rDNA), and also the genes encoding the second largest subunit of RNA polymerase II (RPB2). Furthermore, in order to develop an evolutionary analysis of the hymenophore configuration, we performed stochastic character mapping of ancestral states for the hymenophore type presented in Polyporus s.l. Our study revealed that Pseudofavolus is an artificial group and its species actually nest in a clade within Mycobonia. Therefore, in order to establish a monophyletic group, based upon priority of publication, we re-circunscribed Mycobonia to encompass both stereoid and poroid hymenophore species. Two new combinations are presented from the Neotropics: Mycobonia cucullata and M. miquelii. A new species from tropical Asia, M. yuchengii, is also described. We presente a summary of stochastic mapping of ancestral states estimates of hymenophore type in Polyporus s.l. The ancestral state for Mycobonia clade is estimated to have angular pores.